Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 25, Issue 3, 2025

Programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-L1) are critical immune checkpoints in cancer biology. Multiple small-molecule drugs have been developed as inhibitors of the PD-1/PD-L1 axis. Those drugs promote the formation of PD-L1 homodimers, causing their stabilization, internalization, and subsequent degradation. Drug repurposing is a strategy that expedites the clinical translation by identifying new effects of drugs with clinical use. Herein, we aimed to repurpose drugs as inductors of PD-L1 homodimerization and, therefore, as potential inhibitors of PD-L1.

We generated a hybrid pharmacophore model by analyzing the structures of reported ligands that induce PD-L1 homodimerization and their target-binding mode. Pharmacophore-matching compounds were selected from a chemical library of Food and Drug Administration (FDA)-approved drugs. Their binding modes to PD-L1 homodimers were assessed by molecular docking and the stability of the complexes and the corresponding binding energies were evaluated by molecular dynamics (MD) simulations. Finally, the activity of one drug as promoter of PD-L1 homodimerization was assessed in protein crosslinking assays.

We identified 12 pharmacophore-matching compounds, but only 4 reproduced the binding mode of the reference inhibitors. Further characterization by MD showed that pranlukast, an antagonist of leukotriene receptors that is used to treat asthma, generated stable and energy-favorable interactions with PD-L1 homodimers and induced homodimerization of recombinant PD-L1.

Our results suggest that pranlukast inhibits the PD-1/PD-L1 axis, meriting its repurposing as an antitumor drug.

Crocin (CRO), the primary antioxidant in saffron, is known for its anticancer properties. However, its effectiveness in topical therapy is limited due to low bioavailability, poor absorption, and low physicochemical stability. This study aimed to prepare crocin nanoparticles (CRO-NPs) to enhance their pharmaceutical efficacy and evaluate the synergistic effects of Cro-NPs with doxorubicin (DOX) chemotherapy on two cell lines: human hepatocellular carcinoma cells (HepG2) and non-cancerous cells (WI38).

CRO-NPs were prepared using the emulsion diffusion technique and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Zeta potential, and Fourier transform infrared spectroscopy (FT-IR). Cell proliferation inhibition was assessed using the MTT assay for DOX, CRO, CRO-NPs, and DOX+CRO-NPs. Apoptosis and cell cycle were evaluated by flow cytometry, and changes in the expression of apoptotic gene (P53) and autophagic genes (ATG5 & LC3) were analyzed using real-time polymerase chain reaction.

TEM and SEM revealed that CRO-NPs exhibited a relatively spherical shape with an average size of 9.3 nm, and zeta potential analysis indicated better stability of CRO-NPs compared to native CRO. Significantly higher antitumor effects of CRO-NPs were observed against HepG2 cells (IC50 = 1.1 mg/ml and 0.57 mg/ml) compared to native CRO (IC50 = 6.1 mg/ml and 3.2 mg/ml) after 24 and 48 hours, respectively. Annexin-V assay on HepG2 cells indicated increased apoptotic rates across all treatments, with the highest percentage observed in CRO-NPs, accompanied by cell cycle arrest at the G2/M phase. Furthermore, gene expression analysis showed upregulation of P53, ATG5, and LC3 genes in DOX/CRO-NPs co-treatment compared to individual treatments. In contrast, WI38 cells exhibited greater sensitivity to DOX toxicity but showed no adverse response to CRO-NPs.

Although more in vivo studies in animal models are required to corroborate these results, our findings suggest that CRO-NPs can be a potential new anticancer agent for hepatocellular carcinoma. Moreover, they have a synergistic effect with DOX against HepG2 cells and mitigate the toxicity of DOX on normal WI38 cells.

Tender Coconut Water (TCW) is a nutrient-rich dietary supplement that contains bioactive secondary metabolites and phytohormones with anti-oxidative and anti-inflammatory properties. Studies on TCW’s anti-cancer properties are limited and the mechanism of its anti-cancer effects have not been defined.

In the present study, we investigate TCW for its anti-cancer properties and, using untargeted metabolomics, we identify components form TCW with potential anti-cancer activity.

Cell viability assay, BrdU incorporation assay, soft-agar assay, flow-cytometery, and Western blotting were used to analyze TCW’s anticancer properties and to identify mechanism of action. Liquid chromatography-Tandem Mass Spectroscopy (LC-MS/MS) was used to identify TCW components.

TCW decreased the viability and anchorage-independent growth of HepG2 hepatocellular carcinoma (HCC) cells and caused S-phase cell cycle arrest. TCW inhibited AKT and ERK phosphorylation leading to reduced ZEB1 protein, increased E-cadherin, and reduced N-cadherin protein expression in HepG2 cells, thus reversing the ‘epithelial-to-mesenchymal’ (EMT) transition. TCW also decreased the viability of Hep3B hepatoma, HCT-15 colon, MCF-7 and T47D luminal A breast cancer (BC) and MDA-MB-231 and MDA-MB-468 triple-negative BC cells. Importantly, TCW did not inhibit the viability of MCF-10A normal breast epithelial cells. Untargeted metabolomics analysis of TCW identified 271 metabolites, primarily lipids and lipid-like molecules, phenylpropanoids and polyketides, and organic oxygen compounds. We demonstrate that three components from TCW: 3-hydroxy-1-(4-hydroxyphenyl)propan-1-one, iondole-3-carbox aldehyde and caffeic acid inhibit the growth of cancer cells.

TCW and its components exhibit anti-cancer effects. TCW inhibits the viability of HepG2 hepatocellular carcinoma cells by reversing the EMT process through inhibition of AKT and ERK signalling.